We present the first estimates of moment tensor solutions and probabilistic nonlinear hypocenter locations for the 1968 Belice earthquake sequence, which is the most relevant seismic activity occurred in western Sicily in historical times. This seismic phase, including six earthquakes with magnitude between 5 and 6.4, produced severe damages and fatalities in a sector of the Nubia–Eurasia plate margin, previously considered aseismic. Poorly constrained and often controversial hypocenter locations and focal mechanism solutions available from the literature have led to a long‐lasting ambiguity on the possible causative source of the sequence, also having primary effects on the regional seismotectonic modeling and seismic hazard evaluations. The two main fault models proposed in the literature alternatively assigned a primary role to the north‐northwest‐trending Nubia–Eurasia plate convergence, causing thrust faulting on about east‐trending structures or to the differential foreland retreat driving dextral strike‐slip movements on about north–south‐oriented faults. By focusing on the starting and the most energetic phase of the 1968 sequence, we computed the moment tensor solutions for three of the strongest earthquakes using digitized waveforms and a time‐domain waveform inversion technique. Then, we also analyzed, by means of a Bayesian hypocenter location technique, the spatial distribution of the 1968 earthquakes. All the results indicate that the 1968 Belice sequence was characterized by predominant reverse faulting occurring on about east‐to‐northeast‐trending structures, thus solving the dualism between models previously proposed in the literature. Our findings well agree both with the geodynamic framework governed by the Nubia–Eurasia north‐northwest‐trending convergence and with the geological reconstructions of the regional thrust front in the western Sicily area. The results of moment tensor estimations and nonlinear hypocenter locations furnishing an improved knowledge of the most relevant seismic activity of western Sicily also concur to better constraint the seismotectonic modeling of the region.

中文翻译：

---

1968 年意大利南部 Belice 地震序列的新结果：解决长期存在的成因歧义

我们首次对 1968 年 Belice 地震序列的矩张量解和概率非线性震源位置进行估计，这是历史上西西里西部发生的最相关的地震活动。这一地震阶段包括 6 次 5 至 6.4 级地震，在之前被认为是抗震的努比亚-欧亚板块边缘部分造成了严重的破坏和死亡。文献中可用的震源位置和震源机制解决方案缺乏约束且经常引起争议，导致对该序列可能的成因来源的长期模糊不清，也对区域地震构造建模和地震危险性评估产生了主要影响。文献中提出的两个主要断层模型交替地将主要作用分配给北-西北向的努比亚-欧亚板块辐合，导致约东向构造上的逆冲断层或驱动约南北向断层。通过关注 1968 年序列的开始和最活跃的阶段，我们使用数字化波形和时域波形反演技术计算了三个最强地震的矩张量解。然后，我们还通过贝叶斯震源定位技术分析了 1968 年地震的空间分布。所有结果表明 1968 Belice 层序的特征是主要的逆断层发生在大约东向东北走向的构造上，从而解决了先前在文献中提出的模型之间的二元论。我们的研究结果与努比亚-欧亚北-西北-西趋汇合控制的地球动力学框架以及西西里岛西部区域逆冲锋的地质重建非常吻合。矩张量估计和非线性震源位置的结果提供了对西西里西部最相关地震活动的改进知识，也同意更好地约束该地区的地震构造建模。